Fix for bug 11387, CSS3 :empty selector is not dynamic.

        Add support for dynamically updating elements whose style is affected by :empty when the child count changes.

        Reviewed by olliej, mitzpettel

        fast/css/empty-pseudo-class.html

        * css/CSSStyleSelector.cpp:
        (WebCore::CSSStyleSelector::locateSharedStyle):
        (WebCore::CSSStyleSelector::checkOneSelector):
        * dom/Element.cpp:
        (WebCore::Element::childrenChanged):
        * dom/Element.h:
        * rendering/RenderStyle.h:
        (WebCore::RenderStyle::affectedByEmpty):
        (WebCore::RenderStyle::emptyState):
        (WebCore::RenderStyle::setEmptyState):

LayoutTests:

        Add a new layout test for dynamic :empty selectors.

        Reviewed by olliej

        * fast/css/empty-pseudo-class.html: Added.
        * platform/mac/fast/css/empty-pseudo-class-expected.checksum: Added.
        * platform/mac/fast/css/empty-pseudo-class-expected.png: Added.
        * platform/mac/fast/css/empty-pseudo-class-expected.txt: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@29918 268f45cc-cd09-0410-ab3c-d52691b4dbfc